Vice President Biden made an impassioned appeal Thursday to members of the nation’s oldest civil rights group to rally behind President Obama and reject a Republican vision for the country that Biden said would roll back progress for minorities.

Speaking at the NAACP conference in Houston a day after presumptive GOP presidential nominee Mitt Romney appeared there, Biden delivered a sharp rebuttal to Romney’s contention that his policies would be better for black families than Obama’s have been at a time when unemployment among African Americans is 14.4 percent.

Biden sketched out what he said is the Republican Party’s hostile position toward the middle and working classes on voting rights, health care, taxes and education to argue that a Romney administration would be detrimental to blacks.

The vice president played to the crowd, sending a shout-out to friends in the Delaware delegation and recalling his work on voting rights during his time on the Senate Judiciary Committee.

“Did you think we’d be fighting these battles again?” he said. “I didn’t think we’d be back. I remember working with Republicans — and by the way, this ain’t your father’s Republican Party — on “motor voter” [legislation], expanding the [voting] franchise. Some of these were Republican ideas. This is not the Republican Party’s view today, nor Romney’s. They see a different future in which voting is harder [rather] than easier.”

Biden added, “There’s a lot more to say, but this is preaching to the choir.”

Indeed it was. Polls show that black voters overwhelmingly support Obama, even if they are frustrated by the economy and the unemployment rate, which is far higher among African Americans than the general population.

Whereas Romney drew three sets of boos from the same audience, Biden received a warm welcome and applause throughout. When he said he would wrap up his speech, some in the audience shouted, “No!”

Before Biden spoke, Obama addressed the audience via video message. The president, echoing his campaign stump speech, told the crowd that his administration is committed to a country where “no matter who you are or what you look like or where you come from, America is a place where you can make it if you try.”

On Wednesday, Romney had told the NAACP that Obama has failed in his bid to restore prosperity and security.

“If you want a president who will make things better in the African American community, you are looking at him,” Romney said, drawing boos.

Ticking through a list of Obama’s accomplishments — bailing out the auto industry, signing health-care reform legislation, ordering the killing of Osama bin Laden — Biden argued that the president achieved those feats despite Republican obstructionism.

“They were seas of obstruction,” he said. “Their discipline was amazing. They never let up. But neither has my guy, neither has Barack Obama. He hasn’t given up.”

Biden linked Romney directly to Capitol Hill Republicans, including House Majority Leader Eric Cantor (Va.) and Senate Minority Leader Mitch McConnell (Ky.), and argued that under a Romney administration, they would collude to undo critical reforms.

“Close your eyes and imagine — imagine what the Romney Justice Department would look like,” Biden said, drawing shouts of “No!” from the crowd. “Imagine who he’d recommend to be the attorney general or head of the civil rights division. Imagine what the Supreme Court will look like after four years of a Romney presidency.

“This election, in my view, is a fight for the heart and soul of America,” he continued, adding of Republicans: “These guys aren’t bad guys, they just have a fundamentally different view.”